Another graphene miracle: It can distill booze

Graphene may be one of science's greatest recent discoveries. The one-atom-thick layers of carbon are the thinnest known material in the universe, 100 times stronger than steel, a very efficient conductor of electricity, and, according to new research published this week in the journal Science, a substance that can also be used to distill liquor.

A team of researchers at the University of Manchester wasn't really looking at how graphene might be used to produce stronger spirits. They were examining the ability of graphene sheets to block the passage of gases. They found that graphene was impermeable to all gases and liquids, but it did allow water to evaporate more quickly than if the graphene membranes were not present.

The researchers were working with a membrane called graphene oxide, which is derived from a graphene sheet randomly covered with other molecules. The graphene oxide sheets can be stacked on top of each other, so they are no longer just one atom thick, but they are still hundreds of times thinner than human hair while still remaining strong and flexible.

The unique property of these membranes amazed the scientists. "Helium gas is hard to stop," said lead author, professor Andre Geim, who points out that helium can pass through solid glass. "But our ultra-thin films completely block it," he said. Geim was one of the scientists who pioneered the research of graphene in 2004. He and Konstantin Novoselov won the Nobel Prize in Physics in 2010 and were awarded British knighthoods in December 2011.

Even though the graphene membranes blocked helium, they still allowed water vapor to pass through. "Materials cannot behave any stranger," Geim said in a prepared statement. "You cannot help wondering what else graphene has in store for us."

On a lark, the University of Manchester team decided to see what would happen if they sealed the top of a bottle of vodka with graphene. It was an odd choice, since none of them drink vodka. But the results were even odder: the graphene allowed water from the alcohol to escape, distilling the vodka and making it stronger.

This discovery was not the focus of their new research, but they did report it in their paper. They say they don't foresee a future distillery application for graphene, or any other specific applications that would employ this new information, but they didn't rule anything out.

"The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water," said Geim.

Meanwhile, this week brought several additional graphene discoveries. Researchers at the University of California, Riverside have found that two stacked graphene sheets can work as an electric insulator, while physicists in the U.K. and Spain have found that graphene "doped" with electrodes can become a perfect absorber of light. Another team from China used graphene to mimic the ability of butterfly wings to repel water, and IBM researchers demonstrated the world's fastest graphene transistor. However, these discoveries are unlikely to get as much press as the vodka-distilling vodka.